Headphones are used with both fixed equipment (e.g. home theatre and desktop computers) and portable devices (e.g. mp3 players and mobile phones) to reproduce sound from an electrical audio signal. To maximise the clarity of audio playback, headphones are typically designed to prevent as much background (ambient) noise as possible from reaching the user's eardrums. This can be achieved using both passive and active noise control. Passive noise control involves attenuation of the acoustic signal path to the ear canal, whilst active noise control involves the generation of a noise cancellation signal to interfere destructively with the background noise.
There are some scenarios, however, where the detection of background noise is desirable. For example, some people enjoy listening to music on their mp3 players whilst walking around outside. In busy urban surroundings, such as city centres, there is often a lot of traffic on the roads. In this situation, headphones can inhibit a user's ability to detect approaching traffic, and therefore present a potential health risk.
Another example is for call centre staff who require audio headsets for simultaneous conversation and typing, and who need to be able to hear instructions from their superiors in the office whilst involved in a telephone conversation with a customer.
One way of overcoming this problem is to use a single earpiece (monaural) for audio reproduction, rather than an earpiece for each ear (binaural). However, because each ear detects a different sound, monaural headphones can be disorientating for the user. In addition, two earpieces are required in order to play two audio channels simultaneously, so stereo sound cannot be reproduced with monaural headphones.
Another option is to use an augmented reality audio (ARA) headset, which allows the playback of both primary and background audio signals at the same time. Nevertheless, there are scenarios where a user may still wish to block out some or all of the background sounds. For example, if a user is travelling by bus, he/she may not wish to hear the conversations of other passengers or the rumble of the wheels on the road surface whilst listening to music on an mp3 player, and so would appreciate the option of being able to cancel the background sounds. On the other hand, the same user may wish to hear some of the background sound, such as travel announcements, from the bus conductor or driver.
In these situations, the use of active noise control (ANC) with an ARA headset may be advantageous. However, currently available ANC headsets tend to cancel out all environmental sounds and are therefore unsuitable for this purpose.
The apparatus and associated methods disclosed herein may or may not address these issues.
The listing or discussion of a prior-published document or any background in this specification should not necessarily be taken as an acknowledgement that the document or background is part of the state of the art or is common general knowledge. One or more aspects/embodiments of the present disclosure may or may not address one or more of the background issues.